The mechanical properties of three types of bone: deer's antler, cow's femur and fin whale's tympanic bulla, are compared. The antler has a very high work of fracture, the bulla a very low one. The bulla has a very high modulus of elasticity, the antler a low one. The cow's femur is the strongest in bending, the bulla is very weak. It is shown how these mechanical properties, which are associated with markedly different amounts of mineralization, nicely suit the bones for their differeing functions.